Off Side Rear Brake Overheating

[Hardcore]

aving a bit of an unusual issue here so some backround first. Please bear with me on this as it's doing my head in and want to make sure i cover all the points

Approx 18 months / 2000 miles ago i replaced / did the following with my MK1 vRs rear brakes.

 

2 new handbrake cables.

2 new rear calipers

New discs

New pads

All 4 calipers bled.

New anti squeal shims fitted on rear calipers

New sliders fitted on rear calipers

 

End result was good solid handbrake, and rear brakes were perfect.

 

1 issue that did happen is the reservoir went dry and took a big gulp of air, but after bleeding the brakes several times it looked like all air got out and has been fine for almost 2 years now.

I noticed however the other day i could smell cooking bads and on further inspection the driver side rear disc was cooking hot.

 

I removed the wheels and noticed that although the handbrake mechanism was fully released on the caliper and although the wheel was freely spinning, the pads were stuck in the carriers.

I removed the pads, filed the edges to clean / remove all the rust.

Cleaned the carriers.

Regreased pad back plate and fitted new anti squeal shims and mad sure pads were able to move okay.

Sorted, right?

No! sadly.

 

Rear brake is still overheating for some reason but handbrake doesn't seem to be sticking.

The only thing i can think of is that rear caliper is coming on before the other brakes and is doing more work.

My next plan is to remove pads again, wind the pistons all the way back in both rears and bleed all the brakes again then re-test.

Wondering if it's a trapped airlock that got into the ABS pump and now it's moved to a pipe.

When car is tested on the driveway with the handbrake released you can push it back with zero effort and no binding. With handbrake on, it holds. So unsure if it's fully releasing why it's cooking the brake on a short drive.

Anyone else had a similar issue, or any other suggestions?

 

 

 

[StevesTruck]

I don't think it's going to fix it, with it only being one wheel, but start by popping the vacuum hose off the servo and see if it releases, just in case it is the none return valve. I don't think it's going to be, but always do what's easy first.

 

Realistically, it sounds like you've had a bit of a mare with it and had to spend a lot of time bleeding it through, so I'd probably drop the rear calipers off and see if they'll wind back at all. I'd imagine one's pushed out a bit. 

[Breezy_Pete]

Wheel bearing?

[Hardcore]

3 hours ago, StevesTruck said:

I don't think it's going to fix it, with it only being one wheel, but start by popping the vacuum hose off the servo and see if it releases, just in case it is the none return valve. I don't think it's going to be, but always do what's easy first.

 

Realistically, it sounds like you've had a bit of a mare with it and had to spend a lot of time bleeding it through, so I'd probably drop the rear calipers off and see if they'll wind back at all. I'd imagine one's pushed out a bit. 

 

I get you. If it's the offside rear getting cooked, i'd expect the nearside front as well due to any potential rubbing, but since it's easy enough to do that, then no harm in trying it.
I've had it 7 years now and the amount of times i've had the rear brakes in bits, i've never wanted to go back to drum brakes so much in my life.

I had the pads off at the weekend just there inspecting / cleaning everything but i'll do it again i think, crack nipples open to check for air and wind pistons back at the same time so they can adjust themselfs again as needed.

 

2 hours ago, Breezy_Pete said:

Wheel bearing?

It's possible, but i've not heard any of the usual wheel bearing noises. 
What's the best way to check for the rear bearings on these? Wheel on, horizontal / vertical push / pull check and freespin? 

Someone mentioned it could be an internally collapsed hose as well causing slow fluid return when releasing the pedal.

[J.R.]

3 hours ago, Hardcore said:

I removed the wheels and noticed that although the handbrake mechanism was fully released on the caliper

 

Are you 100% sure of that?

 

Have you compared the angle of the handbrake actuator arms on each caliper to the other?

 

Have you looked at the compensator arm just behind the handbrake with the rear ashtray/armrest removed? If one cable is adjusted more than the other and/or the arm is not at 90° to the cables then someone has been trying to resolve this before you if you have not adjusted it.

 

It could also quite simply be a sticking piston.

 

I too spent far too long trying to resolve a sticking handbrake on one caliper, I rebuilt the calipers twice and had them apart multiple times, in the end I gave up (unlike me) and bought some super cheap calipers from China, no more overheating rear brake but guess what happened to the guy I sold the car to!!!!

 

There are some springs from an earlier vehicle (Golf?) that can be fitted to ensure the caliper operating levers return fully

[Hardcore]

1 minute ago, J.R. said:

 

Are you 100% sure of that?

 

Have you compared the angle of the handbrake actuator arms on each caliper to the other?

 

Have you looked at the compensator arm just behind the handbrake with the rear ashtray/armrest removed? If one cable is adjusted more than the other and/or the arm is not at 90° to the cables then someone has been trying to resolve this before you if you have not adjusted it.

 

It could also quite simply be a sticking piston.

 

I too spent far too long trying to resolve a sticking handbrake on one caliper, I rebuilt the calipers twice and had them apart multiple times, in the end I gave up (unlike me) and bought some super cheap calipers from China, no more overheating rear brake but guess what happened to the guy I sold the car to!!!!

 

There are some springs from an earlier vehicle (Golf?) that can be fitted to ensure the caliper operating levers return fully

99% sure. I had a sticking handbrake cable previously, so every time it stuck i had to go under the car and release the caliper by hand. I done it probably 50+ times during then and i the piston actuator arm is heading is moving freely on these calipers.

I haven't compared it to the other side however. But i'd expect the wheel to be binding after releasing the handbrake if it was related to them, and the wheel spins freely every time after releasing the handbrake during testing on the driveway and when i was inspecting the calipers / handbrake over the weekend.

The compensator arm has never sat perfectly straight on my car ever and i've replaced both rear cables twice, with new calipers, discs / pads both times over the 7 years i've had it. But when i apply the handbrake, it generates equal force to each rear wheel, and when i release the handbrake, both rear wheels spin freely each time.

This is my 4th set of calipers on the car in 7 years and since i done them 2000 miles / 18 months ago i'd be a little annoyed to have to do one again. Hopefully if the weather warms up a little i'll get out and do some more testing so at least if i haven't fixed it or figured it out i can come back with some more useful information from it.